Manufacture of flexible metallic tubing



. July 28, 1925. 1,547,609

. W. C. ROBINSON ET AL MANUFACTURE OF FLEXIBLE METALLIC TUBING Original Filed Feb. 16, 1922 2 Sheets-Sheet IN VE/V TOR v Umw/smg July 28, 1925. 1,547,609

w. c. ROBINSON ET AL MA XNUFACTURE O'l FLEXIBLE METALLIC TUBING Original Filed Feb. 16, 1922 2 Sheets-Sheet 3 F'IG.Z-

W I T/VESS E 6' latented July 28, 1925.

UNITED STA g 1,547,699 PATENT oFFic'E- WILLIAM C. ROBINSON, OP PITTSBU RGH, ANI) GEORGE E. PHILLIPS, QF BADEN, PENN- SYLVANIA, ASSIGNORS TO NATIONAL MOLDING COMPANY, OF. PITTS- BUBGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

MANUFACTURE OF FLEXIBLE METALLIC 'IUBINCn Application filed February 16, 1922, Serial No. 536,904. Renewed May 1, 1925.'

T 0 all whom it may concern:

Be it known that we, WILLIAM C. RoamsoN, a citizen of the UnitedStates, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, and GEORGE E.

.PiuLurs, asubject of the King of Great Britain, residing at Baden, in the county of Beaver and State of Pennsylvania, have invented or discovered certain new and useful Improvements in the Manufacture of Flexible Metallic Tubing, of which improvements the following is a specification.

It is the object of the present invention to provide flexible metallic tubing of novel cross-sectional contour, whereby it may. be more adaptable to use in particular situations or relations where its use is desired, more especially such as exist or may arise when such tubing is used as conduit for electrical conductors. Flexible metallic tubing of the type to which the invention relates is formed of successive helical convaluations of a strip or strips of hard metal to form a tube which is circular in crosssection, the strip or strips being of such cross -sectional form that the edges of successive convolutions are interengaged in such way as to permit of limited axial movement of the convolutions relatively to one another,

thus attaining the desired flexibility of the tubing as a whole. This true of tubing and various methods of its m.-.;ufacture are so well known to those skilled in the art that further description is unnecessary.

By the present invention we produce flexible metallic tubing of non-circular crosssectional contour, and preferably of generally elliptical form. Such elliptical tubing has the advantage that under certain circumstances a given combination of conductors can be carried in a conduit of smaller internal area. Also where it is desired to conceal the conduit in the wall. or ceiling r of a room, a lesser depth of plaster than' necessary in the case of a circular conduit will be suflicient to cover it. And generally speaking it is better adapted to use in some of the present commercial installations.

In the accompanying drawings we have illustrate-d conventionally a means which is suitable for the practice of the invention. Figure 1 is a front view of a pair of shaping rolls. Fig. 2 is a sectional side elevation, showing the shaping of single-strip tubing.

Fig. 3 is a cross-section on the line III-III;

and Fig. 4 a cross-section on the line IVIV of Fig. 2'. Fig. 5 shows a two-strip tubing,

a portion of which has been shaped;

In suitable bearings in thehousing 1 are mounted the shafts 2, 3 of the rolls 4, 5, the

lower'roll-shaft 2 being extended for connection with a suitable source of ower (not shown). The working faces of t e rolls are provided with diagonal grooves 6 having a slope corresponding to the pitch of the coils 7 of the tubing 8 to be operated upon, and of a size which will permit the successive grooves to effectively engage the successive coils both above and below, and

thus draw the tubing through the pass form, as showr in Fig. 4. 'By this operation T local distortion of the tubing it; 'revented and a symmetrical and uniform product is obtained. a

The invention is not necessarily limited to the production of tubing of elliptical form, since it is obviously adaptable to the formation of the tubing into other non-circu-. lar shapes or such character that the active forming surfaces may be cooperatively ar-.

ranged to so control the operation that it may be carried out without local distortion of the tubing. 1

Ive claim as our invention:

1. The method of manufacture of flexible metallic tubing of non-circular cross-sectional contour, which consists in helically coiling a metallic istrip or strips into successive intcrengz Ting convolutions, and then rolling the tubin to the form desired;

2. The method of manufacture of flexible metallic tubing of non-circular cross-sectional contour, which consists in helically coiling a. metallic strip or strips into successive interengaging 'convolutions of circular form, and then rolling the tubing to the form desired between rolls having working sur faces provided with transverse grooves engaging said convolutions.

3. The method of mnpufacture of flexible metallic tubing of elliptical cross-sectional: contour, which consists in helically coiling a metallic strip or strips into successive interengagmg convolutions of circular form, and then flattening diametrically opposite portions of thetubing. r

cessive inter-engaging convolutions of air-- cular form, and then flattening diametrically opposite portions of the tubing between rolls provided ith transverse grooves-engaging 15 said convoiutions.

In testimony ivhcreof '0 have hereunto set onrhands;

\VILLIAM C. ROBINSON. GEORGE E. PHILLIPS.

lVitn 'sses:

r I DA'ximu. A. CHRISTYJ" 

